An arrangement of this kind is known from German patent application DE 101 51 778 A1. In the arrangement described in that publication, first of all a magnetic selection field having a spatial distribution of the magnetic field strength is generated such that a first sub-zone having a relatively low magnetic field strength and a second sub-zone having a relatively high magnetic field strength are formed in the examination zone. The position in space of the sub-zones in the examination zone is then shifted, so that the magnetization of the particles in the examination zone changes locally. Signals are recorded which are dependent on the magnetization in the examination zone, which magnetization has been influenced by the shift in the position in space of the sub-zones, and information concerning the spatial distribution of the magnetic particles in the examination zone is extracted from these signals, so that an image of the examination zone can be formed. Such an arrangement has the advantage that it can be used to examine arbitrary examination objects—e.g. human bodies—in a non-destructive manner and without causing any damage and with a high spatial resolution, both close to the surface and remote from the surface of the examination object.
A similar arrangement and method is known from Gleich, B. and Weizenecker, J. (2005), “Tomographic imaging using the nonlinear response of magnetic particles” in nature, vol. 435, pp. 1214-1217. The arrangement and method for magnetic particle imaging (MPI) described in that publication takes advantage of the non-linear magnetization curve of small magnetic particles.
Intra-cerebral or intra-cranial bleedings can be detected in situ during a normal diagnostic scan with established imaging modalities, like CT or MRI. This is general practice during the differential diagnosis of neurological incidents to allow for the distinction between ischemic stroke and bleeding. This, however, rules out patients who need constant monitoring for bleeding, e.g. after a dissection of a cerebral or cranial arterial or patients that undergo lysis therapy where one of the major complications is the occurrence of spontaneous bleeding.
The commonly known modalities used for medical imaging that can be used to detect bleeding, e.g. MRI (Magnetic Resonance Imaging) or CT (Computed Tomography), are only available for a limited amount of time, e.g. for a diagnostic scan. However, patients who need constant monitoring for bleeding need a system that is constantly available or available periodically and can be made available with very little effort.